Fumigant mixtures of ethzlene bromide and methylene chloride



-atented n g- FUMIGANT g ll ;;IhlS invention-relates :to fumigants fand is particularly, concerned with. ,new i and improved mixtures and, to a methodzfor f-umigatinglinsect inf ested-grainlq iji I p ,j -Manyl volatile organic compounds have been suggested,as,fumigants-and particularly for the treatment of stored grain. corftrolofinsectinfestation is conveniently accomplished by applying the fumigant toxicant in liquid form upon the surface of the grain and permitting the fumes to pass downwardly through the body ofithe stored product. However, many common liquid fumigants are selective in their action andare effective against only a few of the major grain infesting insects. Other toxicants are adsorbed or absorbed by the grain in such quantity as to impart undesirable taste and odor characteristics to flour prepared therefrom, whereby baked goods containing the flour are unpalatable. Still other suggested fumigant materials are explosive or adversely aflect the germinating properties of the grain.

A particularlydisadvantageous feature in the v conventionalus of rnanyhnown 'fumigant. compositions is the failure of the latter to control insect infestation at'all' levels of the stored grain. Thus a material which in laboratory or experimental operations may-control common grain infesting insects at low toxicant concentrations, in large scale treatmet of deep bins and granaries may give surface kill onl or be eflective only through the middle or at the bottom of the stored grain mass. Since the survival of even afew live insects permits the rapid build-up of the infesting' organisms, such fumigants are generally unsatisfactory. To avoid the irregular results attributable to stratification of fumigant vapors, large excesses of thetoxicant are frequently employed. While this may accomplish an improved kill of insects, the practice is economically unattractive and the resulting high concentrations of toxicant increas'e the possibility of'injuryto the grain; It is 'an-"obj ect of' tli" present invention to pro vide a new and improved fumiga'nt composition in insects generally. It ovide a such composition which i qt jbeis lbject -toathe disadvantages in se u qahe e s a e-s ewed m n known m lt is' a'n aaaine'n'n obiect 'tofprovide a fumigantmixturewhich be effective at lower concentrations" than many known fumigants and accomplish the totalllkilliof insectswithout impartingi'zundesirable properties to the treated 'A' furthenobject' :isxto provide a method for; the t fumigation. of. stored" grain which will accomplish a complet kill of insects at all levels PATENT MIXTURES or ETHYLENE BRO- MIDE AND METHYLENE CHLORIDE 'Fred w. fil leteherfand Eugene Kenaga, Midland,

Miohl, as'sign'ors to The Dow Chemical Com '--'-pany; Midland, Mich, a corporation-,of.Michi- No Drawing, Application January 1', 1945, ;SerialNo.5'l1 ,018'

. (ores- 225) r in the grain," Other objects will become apparent from the followingspecificationand examples.

. Accordingto the presentinvention, improved fumigant mixtures are provided which comprise as a major toxicingredien't'a solution of ethylene bromide in methylene chloride. These new fumigants have been found superior withrespect to their control of grainv parasites, particularly in bin fumigations. I A further advantage resides in the fact that with such compositions, the use of high pressure containers and special applicators, as required with many volatile organic materials is avoided. Also, the compositions do not adversely afiect the germinating properties of the treated grain or impart odor or taste thereto.

The compositions are substantially non-flammable.

1 The invention further provides a procedure whereby grain stored in bins is treated with the new ethylene bromide-methylene chloride mixtrue to obtain an economical, efiicient, and completecontrol of weevils, borers, and beetles. This procedure comprises introducing the fumigant mixture into the top of a filled bin, granary, elevator, etc., and ontothe summer the grain.

lneling elfect avoids the inconsistent control frequently obtainedwith many liquid organic fumigant materials.

Any substantial amount of ethylene bromide may be employed with the methylene chloride to obtain compositions of improved properties. Th

preferred; range of proportion consists of from 2.5. to20 parts by volume of ethylene bromide dis- "Withrsuch-mixtures 100 per cent control at all levels of stored grain hasbeen obtained undera variety...'of temperature conditions. A definite synergistic eiiect as regards insect toxicity has been, observed! for these compositions-,

y The amounts ofthe new compositions required to accomplish control of insects at all levels of the stored grain are-relatively small. From about '1 to 3 gallons of the mixture per 1000 bushels of grain 'gives complete control of common weevil 'and beetle pests. Even smaller amounts are feflective in shallow bins or "where other known fumigants are employed in combination therewith.

' 3 7 While the foregoing description is directed par- Comp B ticularly to the bin fumigation of grain, it is to Ethylene bromide ga,llons 1 be understood that the new fumigant products Methyl n chloride do 15 may also be employed in vault fumigation, housecm rm "pounds 30 hold fumigation, and the like, wherever a highly compost-m 0 effective non-explosive toxicant material ,is renous 1 quired. In such use the compositions are sufi zi 2 E32 perior to hydrogen cyanide by reason or reduced 1 f rg mt '5 toxicity to humans and greater ease of handling. me am ds The following examples illustrate the inven- 10 (Ethnic) tion but are not to be construed as limiting the composition-D same: Ethylene bromide irnllrmc 1 X E 1 Methylene chloride do.. Varying amounts of ethylene bromide were Betamethanyl'cmonde 25 dissolved in methylene chloride to obtain liquid 15 p i i n E fumigant mixtures. These products were sprin- Gallons kled on the surface of wheat stored in an air- Ethylene br 1 tight bin 10 feet in depth. Caged Tribolium con- M y ene ch oride 10 fusum adults (confused flour beetle) were dis- Ethylene chloride 10 persed in and through the grain at various levels prior to application of the fumigant. After application of the toxic mixture, the bin was closed and allowed to stand for 3 days. The caged insects were then removed from the grain and examined to determine the degree of control accomplished. The following table sets forth the results obtained with the several compositions.

25 gredient a solution of from 2.5 to 20 per cent by volume of ethylene bromide in methylene chloride at the top of the bin and onto the surface of the stored grain.

Table I I Per Cent. by Pm- Cent by Amount of Fvilllllllllle LIYOEIIFE Mlxlm r1:011 sl-er Cent ggi gg .l y one ct y one 1,000 us e s uriace Kill Bromide Chloride of Grain Lew! Level Gala. [00 (2 3. 36 100 87 31 100 O 4. 48 100 100 31 100 0 5.6 100 100 37 100 0 6. 7 100 100 100 2. 5 97. 5 2. 0 88 100 100 b. 0 95. 0 2. 0 100 100 100 10. l) 90. 0 2. 0 100 100 100 I 0. 0 80. 0 2. 0 100 100 98 I so. 0 7o. 0 2.0 100 100 33 (l 100 2.0 0 56 14 EXAMPLE 2 2. A fumigant composition including as an ac- In a similar fashion solutions of ethylene brotive toxic ingredient a solution of from 2.5 to 20 mide in methylene chloride were applied to wheat P cent by Flume of ethylene bromide in bins for the control of rice weevil. The following table sets forth the results obtained:

methylene chloride.

3. A fumigant composition comprising a Table II Per Cent by Per Cent by Amount of glfillullllfl Mvollurlno 1M ogrotgre gel; sPrefr Cell?111 gaigig i y one ct y one us e u ace Bromide Chloride of Grain Len] Level Gala. 100 0 3 100 90 100 0 4 100 100 14 2. 5 97. 5 2 100 100 1(1) 5. 0 95. O 2 100 100 100 10.0 90.0 2 100 100 100 20. 0 80. 0 2 100 100 100 30. 0 70. 0 2 100 100 EXAMPLE 3 volatile liquid including a solution of from 5 to Other compositions which may be employed substantially as described in the foregoing examples for the control of organisms in stored wheat, corn, rice, barley, buckwheat, oats, rye, etc., or for vault or chamber fumigation of insect infested articles and products include the following:

Composition A The following references are of record in the file of this patent:

Parts by UNITED STATES PATENTS 7 volume Number Name Date Ethylene bromide 10 2,324,471 Allen et a1. July 20, 1943 Methylene chloride 70 2,324,472 Allen et a]. July 20, 1943 Carbon tetrachloride 20 1,920,026 Tischler July 25, 1933 

